AlF 4 ? and vanadate stimulate chloride secretion in rabbit colon by a Ca2+-dependent mechanism

Abstract

Stripped rabbit descending colon mucosae were studied in vitro in modified Ussing chambers to determine the effects of AlF4- and vanadate on Cl- transport. Serosal additions of AlF4- and vanadate increase short circuit current (Isc) and tissue conductance, while luminal addition of the agents is ineffective. Addition of aluminium potentiates the effect of NaF on Isc. AlF4- and vanadate increase serosal-to-mucosal flux of 36Cl without affecting mucosal-to-serosal flux. The effects of these agents on Isc are markedly inhibited by serosal addition of bumetanide and depend on the presence of Na+ in the serosal bathing solution. The effects of AlF4- and vanadate on Isc are dependent on the presence of Ca2+ in the bathing solution, and are completely inhibited by indomethacin, but the effect of forskolin is not affected by the removal of Ca2+ from the bathing solution and the addition of indomethacin. AlF4- and vanadate significantly increase the level of inositol phosphate metabolites. The results indicate that AlF4- and vanadate increase Cl- secretion in the rabbit colon via an increase in prostaglandin synthesis which is mediated by the increase of intracellular Ca2+ concentrations.

Effects of Luminal ATPase Inhibitors on Electrogenic Ion Transport in Rat Distal Colon1

“…Thus, a potential interaction with ion transport processes in secretory epithelia may occur. In fact, VO 4 3Ϫ has been shown to modulate CFTR activity [12] and to stimulate chloride secretion in both T 84 human cell line and native human colon [13,14] and rabbit colon [15]. Yet, little is known about its effects on intact native mammal …”